Crystal growing apparatus

Abstract

In a high rate pulling with a cooler 10 surrounding a single crystal 8, steam explosion by leakage from the cooler 10 is prevented. Flow rates La, Lb of cooling water are measured by flowmeters 14 a, 14 b on a cooling water inflow side and cooling water outflow side of the cooler 10. When flow rate difference ΔL (La−Lb) determined from the flow rates La, Lb exceeds 20 cc/minute, open/close valves 15 a, 15 b, 15 c are operated to stop water supply to the cooler 10 and drain outward the cooing water in the cooler 10.

What is claimed is:  
     
       1. A crystal growing apparatus which grows a single crystal from a melt by a CZ method, comprising: 
       a tubular cooler which is provided so as to surround the single crystal grown from the melt, and is forcedly cooled by cooling water flowing through the cooler to cool the singled crystal;  
       flowmeters which are provided on a cooling water inflow side and a cooling water outflow side of said cooler, and measure flow rates of the cooling water on the respective sides; and  
       an abnormality detecting unit which determines a flow rate difference from said flow rates of said cooling water measured on said cooling water inflow side and cooling water outflow side of said cooler, and detects abnormal leakage in said cooler from said flow rate difference.  
     
     
       2. The crystal growing apparatus according to  claim 1 , wherein said flowmeters are capable of measuring the flow rates under 20 cc/second. 
     
     
       3. The crystal growing apparatus according to  claim 2 , further comprising automatic valves which are respectively provided on the cooling water inflow side and cooling water outflow side of said cooler, and operated by an abnormality detecting signal output from said abnormality detecting means. 
     
     
       4. The crystal growing apparatus according to  claim 3 , wherein the automatic valve on the inflow side is an open/close valve for opening and closing a water supply pipe, and the automatic valve on the outflow side is a switch valve for switching a pipe line from a usual drain pipe to an emergency drain pipe. 
     
     
       5. The crystal growing apparatus according to  claim 1 , further comprising automatic valves which are respectively provided on the cooling water inflow side and cooling water outflow side of said cooler, and operated by an abnormality detecting signal output from said abnormality detecting means. 
     
     
       6. The crystal growing apparatus according to  claim 5 , wherein the automatic valve on the inflow side is an open/close valve for opening and closing a water supply pipe, and the automatic valve on the outflow side is a switch valve for switching a pipe line from a usual drain pipe to an emergency drain pipe.